@Test
  public void singleValuedMapShouldNotContainKeyForSingleValueWithKeyMismatch() {
    // given
    CaseInsensitiveRegexMultiMap multiMap = multiMap(new String[] {"keyOne", "keyOne_valueOne"});

    // then
    assertThat(multiMap.containsKey(not("keyOne")), is(false));
  }
  @Test
  public void singleValuedMapShouldContainKeyForSingleValue() {
    // given
    CaseInsensitiveRegexMultiMap multiMap = multiMap(new String[] {"keyOne", "keyOne_valueOne"});

    // then
    assertThat(multiMap.containsKey(not("notKeyOne")), is(true));
  }
  @Test
  public void multiValuedMapShouldNotContainKeyForMultipleValuesWithKeyMismatch() {
    // given
    CaseInsensitiveRegexMultiMap multiMap =
        multiMap(
            new String[] {"keyOne", "keyOne_valueOne"},
            new String[] {"keyTwo", "keyTwo_valueOne", "keyTwo_valueTwo"},
            new String[] {
              "keyThree", "keyThree_valueOne", "keyThree_valueTwo", "keyThree_valueThree"
            });

    // then
    assertThat(multiMap.containsKey(not("key.*")), is(false));
  }
  @Test
  public void multiValuedMapShouldContainKeyForMultipleValues() {
    // given
    CaseInsensitiveRegexMultiMap multiMap =
        multiMap(
            new String[] {"keyOne", "keyOne_valueOne"},
            new String[] {"keyTwo", "keyTwo_valueOne", "keyTwo_valueTwo"},
            new String[] {
              "keyThree", "keyThree_valueOne", "keyThree_valueTwo", "keyThree_valueThree"
            });

    // then
    assertThat(multiMap.containsKey(not("notKeyTwo")), is(true));
  }